<?php
abstract class Tree {
    abstract public function getPrint();

    //设置名称
    public function setName($name) {
        die ('not this method: setName');
    }
    //获取名称
    public function getName() {
        die ('not this method: getName');
    }
    //设置描述
    public function setDescription($description){
        die ('not this method: setDescription');
    }
    //获取描述
    public function getDescription(){
        die ('not this method: getDescription');
    }
    public function getKey($i)
    { die ('not this method: getKey');

    }
    //添加节点
    public function add(Tree $menu){
        die ('not this method: add');
    }
    //设置节点
    public function set($i, Tree $menu){
        die ('not this method: set');
    }
    //删除节点
    public function removeByKey($i) {
        die ('not this method: removeByKey');
    }

    public function removeByMenu(Tree $menu) {
        die ('not this method: removeByMenu');
    }

}